Flame-retardant polylactic acid fiber with fluorescent effect

Abstract

The invention discloses a flame retardant polylactic acid fiber with fluorescent effect, which is obtained by electrostatic spinning after polylactic acid and a flame retardant fluorescent agent are dissolved in a solvent; its raw materials are composed of 50-100 parts of polylactic acid and 10-50 parts of flame retardant fluorescent agent by mass. The flame retardant fluorescent agent is synthesized from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and pyrene methanol acrylate, and this flame retardant with fluorescent properties can be closely combined with polylactic acid fiber. The polylactic acid fiber prepared by the present invention shows fluorescent effect and more excellent flame retardant properties compared to the polylactic acid fiber added with a single fluorescent agent or flame retardant, so that the polylactic acid fiber is more widely used.

Description

Technical Field

[0001] The invention belongs to the technical field of flame retardant polymer fibers, and in particular relates to flame retardant polylactic acid fibers with fluorescent effects. Background Art

[0002] At present, artificially synthesized polymer fiber fabrics are widely used in the textile industry. Take my country as an example. On the one hand, more than 10 million tons of polyethylene terephthalate (PET), a polyester produced from non-renewable petroleum resources, are consumed every year. On the other hand, due to its difficult degradation properties, whether the discarded textiles are landfilled or incinerated, it will cause serious environmental pollution problems.

[0003] Therefore, in order to solve this problem, biodegradable polymers are gradually being widely used, and polylactic acid is one of them. Polylactic acid (PLA) is polymerized from lactic acid produced by biological fermentation; it comes from nature and belongs to nature. It can be considered that during the life cycle of PLA, its carbon emissions are zero. Therefore, it is bound to be an important development trend for bio-based degradable polymers represented by PLA to replace PET and other difficult-to-degrade polymers for textile production and application.

[0004] However, a big disadvantage of polylactic acid itself is that PLA itself is not flame resistant, especially when polylactic acid is prepared into fiber fabrics, its surface area increases and it is easier to burn. Therefore, the flame retardant properties of polylactic acid fibers must be improved. At the same time, as modern society becomes more and more diversified, the functional requirements for such biodegradable fabrics are also getting higher and higher, and a single functionality can no longer meet the needs. For example, for night workers (police, night runners, etc.), their clothing is not only required to be flame retardant to reduce the fire hazard caused by the flammability of the textiles themselves, but also to have fluorescent properties in order to improve the safety of night activities; for example, anti-counterfeiting packaging in the packaging industry requires not only flame retardant properties but also fluorescent properties.

[0005] At present, the main method to solve the problem of flammable fibers is to add flame retardants to the fibers. For example, CN114921870A discloses a method of blending and melt spinning to blend nitrogen-phosphorus-silicon flame retardants into polylactic acid fibers, but it only achieves a flame retardant effect. For example, CN111349318 blends nitrogen-based flame retardants, phosphorus-based flame retardants and fluorescent colorants into polyester, so that the prepared fiber fabric has both flame retardant effects and fluorescent properties. However, the above-mentioned method of adding flame retardants and fluorescent agents to the polymer matrix separately also has its limitations: such as complicated procedures, and the two fillers may interact with each other, or weaken the flame retardant or fluorescent properties, and cannot achieve a good effect. Therefore, how to improve the flame retardancy of the fiber itself while achieving a fluorescent effect is still a big challenge. Summary of the invention

[0006] To this end, the present invention provides a flame-retardant polylactic acid fiber with a fluorescent effect, which improves the flame retardancy of the polylactic acid fiber by adding a new type of flame retardant with fluorescent properties, and at the same time gives the polylactic acid fiber strong visible fluorescence. Compared with the polylactic acid fiber added with a single fluorescent agent or flame retardant, the polylactic acid fiber prepared by the present invention exhibits a stronger fluorescent effect and better flame retardant properties, making the polylactic acid fiber more widely used.

[0007] The flame-retardant polylactic acid fiber with fluorescent effect is obtained by electrostatic spinning after polylactic acid and a flame-retardant fluorescent agent are dissolved in a solvent. The raw materials are composed of 50-100 parts of polylactic acid and 10-50 parts of the flame-retardant fluorescent agent by mass.

[0008] The flame retardant fluorescent agent is prepared by synthesizing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and pyrene methanol acrylate, and specifically comprises the following steps:

[0009] (1) reacting pyrene methanol with acryloyl chloride at 0° C. for 12 hours to obtain pyrene methanol acrylate;

[0010] (2) Pyrene methacrylate and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide DOPO were added into a three-necked flask equipped with a condenser and a magnetic stirrer at a molar ratio of 1:1.5 to 1.5:1, and N,N-dimethylformamide was added. The reactants were stirred and dissolved under the protection of an inert gas, and then reacted at 40°C for 6 to 8 hours. After the reaction solution was cooled to room temperature, a large amount of precipitate was precipitated, which was then filtered and washed with acetone, and vacuum dried to obtain a light yellow powder, which was a flame retardant fluorescent agent.

[0011] Furthermore, polylactic acid is dissolved in a solvent to obtain spinning solution A, and polylactic acid and a flame retardant fluorescent agent are dissolved together in a solvent to obtain spinning solution B; spinning solution A and spinning solution B are electrospun together through different electrospinning nozzles to obtain flame retardant polylactic acid fibers with fluorescent effects and different fabric structures.

[0012] The mass fraction of polylactic acid in the spinning solution A is 10-12% w / v; the mass fraction of polylactic acid in the spinning solution B is 12-15% w / v, and the mass fraction of the flame retardant fluorescent agent is 0.6-6% w / v.

[0013] The solvent is a composite solution of dichloromethane (DCM) and N,N-dimethylformyl (DMF) with a volume ratio of 7:3 to 5:5.

[0014] The electrospinning nozzles used in the electrospinning process include single-channel needles, double-channel needles and coaxial needles.

[0015] Furthermore, the electrospinning parameters were set as follows: voltage 15-20 kV, spinning solution flow rate 2-3 mL / h, and receiving distance 12-15 cm.

[0016] The polylactic acid fiber of the present invention has a fluorescent effect, and its fluorescence intensity under the excitation of a wavelength of 270nm is higher than the fluorescence intensity of the polylactic acid fiber containing only DOPO and higher than the fluorescence intensity of the polylactic acid fiber containing only pyrene methanol acrylate.

[0017] The flame retardant and carbonization ability of the polylactic acid fiber of the present invention is better than that of the polylactic acid fiber containing only DOPO flame retardant or only pyrene methanol or only pyrene methanol acrylate, that is, DOPO and pyrene methanol acrylate have the ability to synergistically promote the carbonization of polylactic acid.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] The present invention connects DOPO and pyrene molecules through chemical bonds, and utilizes the fluorescence resonance energy transfer effect between the two to enhance the fluorescence emission intensity. At the same time, pyrene can improve the flame retardant performance of DOPO on polylactic acid fibers. By introducing ester bonds in the molecular structure, the compatibility of DOPO and pyrene with polylactic acid is improved.

[0020] The present invention introduces the novel flame retardant with fluorescent properties into polylactic acid fibers, thereby improving the flame retardancy of polylactic acid fibers and giving the polylactic acid fibers strong visible fluorescence. That is, the polylactic acid fibers prepared by the present invention exhibit stronger fluorescent effects and more excellent flame retardant properties than polylactic acid fibers added with a single fluorescent agent or flame retardant, and the obtained flame retardant polylactic acid fibers with fluorescent effects can meet higher requirements of the clothing and packaging industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the molecular structure of DOPO condensed pyrene methanol acrylate.

[0022] Figure 2 This is a scanning electron microscope photograph of the flame retardant fluorescent lactic acid fiber fabric in Example 1.

[0023] Figure 3 This is a digital photo of the flame retardant fluorescent agent prepared in Example 1 under a 254nm ultraviolet lamp.

[0024] Figure 4 The flame retardant fluorescent agent prepared in Example 1 1 H-NMR spectrum

[0025] Figure 5 2 are the fluorescence emission spectra of the PLA fiber membranes of Example 1, Comparative Example 1 and Comparative Example 2 under 270 nm excitation.

[0026] Figure 6 This is a digital photo of the flame-retardant fluorescent lactic acid fiber fabric in Example 1 under 254nm ultraviolet light. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is further described below in conjunction with specific embodiments, but the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Embodiment 1:

[0029] In this embodiment, flame-retardant polylactic acid fibers with fluorescent effect are prepared according to the following steps:

[0030] 1. Preparation of a flame retardant with fluorescent properties: react pyrene methanol and acryloyl chloride at a molar ratio of 1:1.1 at 0°C for 12 hours to obtain pyrene methanol acrylate. Then add pyrene methanol acrylate and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide DOPO at a molar ratio of 1:1.5 into a three-necked flask equipped with a condenser and a magnetic stirrer, and then add N,N-dimethylformamide, and stir and dissolve the reactants under the protection of an inert gas. Then react at 40°C for 6 to 8 hours, and after cooling to room temperature, a large amount of precipitate is precipitated, which is then filtered and washed with acetone, and finally vacuum dried to obtain a light yellow powder, that is, the flame retardant fluorescent agent DOPO-Py.

[0031] 2. Dichloromethane (DCM) and N,N-dimethylformyl (DMF) were compounded into a 7:3 solution, and then polylactic acid was added to the above solution and stirred at a constant temperature of 40°C for 5 hours to obtain spinning solution A; the mass fraction of polylactic acid was 10%.

[0032] 3. Dichloromethane (DCM) and N,N-dimethylformyl (DMF) were compounded into a 7:3 solution, and then polylactic acid and the flame retardant fluorescent agent DOPO-Py prepared above were added to the above solution and stirred at a constant temperature of 40°C until clear and transparent to obtain a spinning solution B: the mass fraction of polylactic acid was 12%, and the mass fraction of the flame retardant fluorescent agent was 2% (the mass ratio of polylactic acid to the flame retardant fluorescent agent was 6:1).

[0033] 4. The spinning solution B was electrospun through a single-channel spinneret to prepare flame-retardant fluorescent polylactic acid fibers, wherein the voltage was 15 kV, the spinning solution flow rate was 2 mL / h, and the receiving distance was 15 cm.

[0034] The flame retardant properties of the polylactic acid fiber fabric obtained in this example are: UL-94: V-1, LOI: 23.4%; and it has blue fluorescence under 254nm ultraviolet light.

[0035] Embodiment 2:

[0036] This embodiment adopts the same method as Example 1 to prepare flame-retardant polylactic acid fiber with fluorescent effect, the difference being that in step 3, the mass fraction of polylactic acid is 12%, and the mass fraction of the flame retardant fluorescent agent DOPO-Py is 2% (the mass ratio of polylactic acid to the flame retardant fluorescent agent is 6:1), while the mass fraction of polylactic acid is 12%, and the mass fraction of the flame retardant fluorescent agent DOPO-Py is 3% (the mass ratio of polylactic acid to the flame retardant fluorescent agent is 4:1).

[0037] The flame retardant properties of the polylactic acid fiber fabric obtained in this example are: UL-94: V-0, LOI: 26%; and it has blue fluorescence under 254nm ultraviolet light.

[0038] Embodiment 3:

[0039] This embodiment adopts the same method as that of embodiment 2 to prepare flame-retardant polylactic acid fiber with fluorescent effect, except that the ratio of dichloromethane (DCM) to N, N-dimethylformyl (DMF) in step 3 is 7:3, which is replaced by a ratio of dichloromethane (DCM) to N, N-dimethylformyl (DMF) of 5:5. At the same time, electrospinning adopts a coaxial spinneret, spinning solution A is used as the inner solution, and spinning solution B is used as the outer solution.

[0040] The flame retardant properties of the polylactic acid fiber fabric obtained in this example are: UL-94: V-0, LOI: 26.2%; and it has blue fluorescence under 254nm ultraviolet light.

[0041] Embodiment 4:

[0042] This embodiment adopts the same method as that of Embodiment 2 to prepare flame-retardant polylactic acid fibers with fluorescent effect, the difference being that in step 4, electrospinning adopts a dual-channel spinneret, and spinning solutions A and B pass through their respective channels and converge at the needle to obtain fibers with special structures.

[0043] The flame retardant properties of the polylactic acid fiber fabric obtained in this example are: UL-94: V-0, LOI: 26.1%; and it has blue fluorescence under 254nm ultraviolet light.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the patent scope of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0045] In this embodiment, flame-retardant polylactic acid fibers with fluorescent effect are prepared according to the following steps:

[0046] 1. Dichloromethane (DCM) and N,N-dimethylformyl (DMF) were compounded into a 7:3 solution, and then polylactic acid and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) were added to the above solution and stirred at a constant temperature of 40°C until it became clear and transparent to obtain a spinning solution B: the mass fraction of polylactic acid was 12%, and the mass fraction of DOPO was 2% (the mass ratio of polylactic acid to DOPO was 6:1).

[0047] 2. The spinning solution was electrospun through a single-channel spinneret to prepare flame-retardant fluorescent polylactic acid fibers, wherein the voltage was 15 kV, the spinning solution flow rate was 2 mL / h, and the receiving distance was 15 cm.

[0048] The flame retardant properties of the polylactic acid fiber fabric obtained are: UL-94: V-2, LOI: 21.4%; and there is a weak blue fluorescence under 254nm ultraviolet light.

[0049] Comparative Example 2:

[0050] This embodiment adopts the same method as that of Comparative Example 1 to prepare flame-retardant polylactic acid fiber with fluorescent effect, except that in step 1, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) is replaced with pyrene methanol acrylate.

[0051] The flame retardant properties of the polylactic acid fiber fabric obtained are: UL-94: V-2, LOI: 19.1%; and it has blue fluorescence under 254nm ultraviolet light.

Claims

1. A flame-retardant polylactic acid fiber with fluorescent effect, characterized in that: The flame-retardant polylactic acid fiber with fluorescent effect is obtained by electrostatic spinning after polylactic acid and a flame-retardant fluorescent agent are dissolved in a solvent; the raw materials thereof are composed of 50-100 parts of polylactic acid and 10-50 parts of a flame-retardant fluorescent agent in terms of mass fractions; The flame retardant fluorescent agent is prepared by synthesizing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and pyrene methanol acrylate, and comprises the following steps: (1) reacting pyrene methanol with acryloyl chloride at 0°C for 12 hours to obtain pyrene methanol acrylate; (2) Add pyrene methoxide and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide DOPO into a reactor, then add N,N-dimethylformamide, stir and dissolve the reactants under the protection of inert gas, then react at 40°C for 6-8 hours, cool the reaction solution to room temperature to precipitate, then filter and wash with acetone, and vacuum dry to obtain a light yellow powder, which is a flame retardant fluorescent agent; The molar ratio of pyrene methanol acrylate to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide DOPO is 1:1.5~1.5:

1.

2. The flame-retardant polylactic acid fiber with fluorescent effect according to claim 1, characterized in that: Polylactic acid is dissolved in a solvent to obtain a spinning solution A, and polylactic acid and a flame retardant fluorescent agent are dissolved in a solvent to obtain a spinning solution B; the spinning solution A and the spinning solution B are electrospun together through different electrospinning nozzles to obtain flame retardant polylactic acid fibers with different fabric structures and fluorescent effects.

3. The flame-retardant polylactic acid fiber with fluorescent effect according to claim 2, characterized in that: The mass fraction of polylactic acid in the spinning solution A is 10-12% w / v; the mass fraction of polylactic acid in the spinning solution B is 12-15% w / v, and the mass fraction of the flame retardant fluorescent agent is 0.6-6% w / v.

4. The flame-retardant polylactic acid fiber with fluorescent effect according to claim 2, characterized in that: The solvent is a composite solution of dichloromethane and N,N-dimethylformyl, with a volume ratio of 7:3 to 5:

5.

5. The flame-retardant polylactic acid fiber with fluorescent effect according to claim 2, characterized in that: The electrospinning nozzles used in the electrospinning process include single-channel needles, dual-channel needles, and coaxial needles.

6. The flame-retardant polylactic acid fiber with fluorescent effect according to claim 2, characterized in that: The electrospinning parameters were set as follows: voltage 15-20 kV, spinning solution flow rate 2-3 mL / h, and receiving distance 12-15 cm.

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